Spark-plug.



F. LAHAwKIN'S.l SPARK PLUG. AFPUCATION FILED FEB. I2, |915.

Atorneys Fammi De.7,1915.

UNTTED STATES PATENT oEEioE.-

' FRANK E. HAWKINS, OF DEERFIELD, KANSAS, ASSIGNOR OF ONE-RALF TO GEORGE W.

BARNES, OF DEERFIELD,

Kansas.

SPARK-PLUG.

Specification of Letters Patent.

Patented Dee. 7, 1915.

Application led February 12, 1915. Serial No. 7,828.

To all whom z't may concern.'

Be it known that I, FRANK E. HAWKINs, a citizen of the United States, residing at Deerfield, in the county of Kearny and .State of Kansas, have invented a new and useful Spark-Plug, of which the following is a specification.

The pi'esent invention appertains to spark plugs or igniters, and aims to provide a novel and improved device of that character.

One of the objects of the invention is the provision of a spark plug having means whereby a priming charge of gasolene or other fuel may be injected therethrough into the cylinder of the engine, to enable the engine to be started readily.

Another object of the invention is to provide a spark plug of such construction, that it will be self-cleaning, and will therefore not be liable to become fouled or short circuited by the lodging of oil, carbon or other foreign matter upon the electrodes.

A further object of the invention is to provide a spark plug withnovel coperating electrodes.

It is also within the scope of the invention, to construct the spark plug by a unique assemblage of the component parts, whereby theutility of the device is enhanced, and whereby `the device is comparatively simple and inexpensive in construction and serviceable, durable, and eflicient in use.

With the foregoing and other objects in view which will appear as the description proceeds, the invention resides in the combination and arrangement of parts and in the details of construction hereinafter described and claimed, it being understood that changes in the precise embodiment of the herein disclosedl can be made within the scope of what is claimed without departing from the spirit of the invention.

The invention isillustrated in the accompanying drawing, wherein- Figure 1 is a longitudinal central section of the improved spark plug. Fig. 2 is a lower or inner end view of the spark plug. Fig. 3 is a cross sectional view of the plug taken on the line 3-3 of Fig. 1.

In carrying out the invention, there is provided a metallic body l of circular cross section, and having a hexagonal wrench engaging portion 1a. The body 1 is provided below its upper or outer end with an inwardly projecting annular flange or lip 2,

and the body v is further provided with a. downwardly or inwardly projecting hollow extension 4 providing a combustion chamber therein. The extension 4 is tapered downwardly or inwardly from the flange or lip 2, and is coaxial with the main portion of the body 1. The internal bore of the eX1 tension 4 decreases in diameter from the body 1 to the free end of the extension. The body 1 is externally screw threaded so as to screw within the threaded bore or aperture of an engine cylinder, as usual, and whereby the extension 4 will project into the cylinder. The lower or inner face of the flange or lip 2 is dished or conical, as at 5, whereby the fiange or lip 2 decreases in width from its base to its free edge.

A porcelain, mica or similar insulator 6 is carried by the body 1, and embodies an upwardly or outwardly projecting tapered portion 7, and an enlarged base 8 at the basal end of the portion 7. The base 8 seats within the socket 3 of the body 1 and against the flange or lip 2 forming the bottom of the socket, and the base 8 of the insulator is provided with a downwardly or inwardly projecting nipple 9 projecting through the restricted opening 10 formed by the flange or lip 2. The insulator 6 is provided with a central longitudinal bore 11 extending therethrough from end to end, and which receives the central or insulated conductor, as will presently appear.4

e central or insulated conductor comprises a metallic tube 12 engaging snugly through the bore 11 of the insulator and having its end portions protruding from the ends of the insulator. A collar 13 is threaded or otherwise secured upon the tube 12 and bears against the lower end of the lower reduced end portion 9 of the insulator and a retaining nut 14 is threaded upon the upper end portion of the tube 12 for clamping the tube to`the insulator. A metallic washer 15 is preferably disposed between the nut 14 and upper end of the insulator, and the wire or conductor (not shown) is adapted to be clamped between the washer 15 and nut 14. When the nut 14 is tightened, it will be evident that the insulator 6 will be clamped between the nut 14 and collar 13, to secure the tube 12 to the hasl the tapered 'the body and insulator.

priming fuel may beinjected into the engine cylinder throughvthe plug The lower or innerl end of the tube 12 extends to andl slightly beyond the lower or inner end of the extension 4 of the plug body, and the upper or outer end of the tube 12 is normally closed by means of a screw plug or cap 16, which may be readily removed when it is desired to prime the engine.

The insulator 6 is secured to the body 1, by means of a packing and retaining nut 17 threaded into the mouth of the socket 3, and bearing against the shoulder of the insulator formed bythe base 8. Thus, the

base 8 of the insulator will be clamped tightly against the flange or lip 2 of the body. The nut 17 is provided with a tapered bore or aperture 18 surrounding the basal end of the tapered portion 7 of the insulator, and an annular tapered packing 19 is disposed between the walls of the bore or aperture 18 and the walls of the portion 7 of the insulator, whereby when the nut 17 is threaded downwardly or inwardly, it will not only clamp the insulator to the body, but will also com press the packing 19 against the portion 7 for closing the space between This will prevent leakage, as will be apparent.

The lower or inner end of the tube 12 carries the central electrode 20, which is enlarged, or which is of greater cross sectional area than the tube 12. The electrode 20 is in the form of a tubular head carried by the lower or inner end of the tube or conductor 12, and is threaded upon the lower end portion of the tube within the lower end or mouth of the extension 4. The upper portion of the electrode 20 is tapered outwardly or upwardly from the plane of the lower or inner end of the extension 4, as at 21, and provides a sharp corner 22 lying in said plane and cooperating with the adjacent sharp edge 23 formed by the free end of the extension 4, to provide an annular spark gap therebetween. The edges or corners 22 and 23 'of the electrode 20 and extension 4, respectively, provide the sparking points, it being noted that the lower end of the extension 4 provides the outer electrode which surrounds the inner electrode. It will thus be seen that the electrode or head 2O is provided with the annular sparking edge 22 lying approximately in the plane of the outer annular sparking edge or electrode 23, and thatthe electrode or head 20 portion 21 .projecting into c the extension 4. and decreasing in diameter from said sparking edge 22.

The inner electrode 20 is provided with a lower inturned flange or lip 24 seating against the lower end of the tube, 12, and providingla restricted outlet .aperture 25 through which the priming fuel flows from the tube into the cylinder. The flange or lip of the electrode 20 is provided with a depending or. inwardly projecting short nipple 26 surrounding the aperture 25, to cause the riming fuel to drip properly into the cylin er, and to prevent the fuel from flowing around the electrode 20 to the spark ga n use, when the spark plug is secured to the cylinder, it will be evident that by removing the plug or stopper 16, the priming charge of gasolene or other fuel may be injected through the tube 12 into the cylinder, so that the engine may be started readily. After the priming fuel is introduced through the tube 12, the plug 16 is reapplied to the outer end of the tube, for closing the same.

Attention is directed to the fact, thatv the tapered extension 4 of the body 1 provides a` tapered combustion chamber therein, which is contracted in its mouth, it being noted that the outer electrode is formed by the mouth portion of the extension 4, and that the inner electrode is surrounded by the mouth portion of the extension, so thatthe annular spark gapl between the electrodes provides the entrance or throat for the chamber within the extension. Due to the taper of the extension 4 and the portion 21 of the electrode 20, the annular entrance of the combustion chamber within the extension 4 increases in width from the spark gap upward. When the new charge of fuel enters the cylinder, a portion thereof will flow into the combustion chamber within the extension 4, and when the electrical sparking circuit is closed through the body 1 and tube 12, the spark or sparks jumping across the spark gap,.will ignite the fuel for driving the engine, and at the same time, the fuel within the extension 4 will be ignited, and the products of combustion in flowing out through the spark gap from within the extension 4, will blow out any oil, carbon or other foreign matter lodging upon the electrodes. In this manner, the present spark plug or igniter is less liable to be fouled or to become clogged with carbon, and will be self-cleaning, to maintain the efficiency of the plug at all times. This will also prevent the short circuiting of the plug, since no carbon is allowed to remain deposited upon the adjacent or active portions ofthe electrodes. The electrodes also coperate in an effective manner, whereby the -charge of gaseous fuels within the cylinder vwill be fired or ignited, notwithstandingv the fact that the electrical current is o'f lowam'perage. Having thus described the invention,what is lclaimed as new is Y 1. A spark plug comprising a body having a hollow inwardly projecting extension, an insulator mounted within the body, a tabular central conductor extending through the insulator to the end of the extension, the end of the' extension forming an outer tubular electrode, and an inner electrode head threaded upon the inner end of the said conductor within and coperating with the aforesaid electrode, the inner electrode head having an internal annular flange seating against the inner end of the said conductor and forming a restricted outlet aperture for said tubular conductor.

2. A spark plug comprising a body having a hollow inwardly pro'ecting extension, an insulator mounted witlhin the body, a tubular central conductor extending through the insulator to the end of the extension, the end of the extension forming an outer electrode, an-inner electrode secured upon the inner end of the said conductor within and coperating with the aforesaid electrode, the inner electrode having an internal annular flange seating against the inner end of the said conductor, and the said' flange having an inwardly projecting nipple.

3. A spark plug comprising a body having an inwardly projecting hollow tapered extension whose internal diameter decreases from the body to the free end of said eX- tension, the free end of said extension having a sharp edge forming an annular outer electrode, an insulator mounted within the body, a conductor extending through the insulator and having an enlarged head upon its inner end lying Within the outer electrode to provide an annular spark gap therebetween, the head forming an inner electrode and having an annular sparking edge lying approximately in th plane of the outer electrode, the head having a tapered portionprojecting into said extension and decreasing in diameter from said sparking edge.

In testimony that I claim the foregoing as my own, I have hereto affixed my signature in the presence of two witnesses.

FRANK E. HAWKINS. 

